The class 3 OMP of Neisseria meningitidis has eight predicted surface exposed loops. The gene encoding this protein is variable between serotypes in regions (variable regions, Vrs) corresponding to four of these loops. Protective antibodies appear to be raised to conformational not linear epitopes. In order to determine the protective epitopes of this protein, we have constructed synthetic cyclic peptides containing lipid tails, which are inserted into liposomes in an effort to mimic suspected conformational epitopes corresponding to surface exposed loops. Preliminary immunization studies have been conducted in BalbC and C57 Black mice. A variety of ELISA methods for measuring anti-peptide antibody were evaluated and one involving covalently bound peptide was identified as an optimal method. Immune responses to the peptide in mice appear to be variable and may be inversely related to the amount of pre-immunization cross reacting antibody present. A larger study including groups of mice to evaluate the effect of varying the amount of Lipid A present in the liposome preparations will be conducted in the next fiscal year.